I can respect that, though I was talking about areas already open to PvE, so Jeuno isn't a valid example. Any place where one might already fear an incursion (your bad for idling in Whitegate or Bastok [S], for example), wouldn't be any worse for having PvP.
Obvious statement is obvious.
Any event is fringe if it doesn't offer much of anything. Would you do Salvage time after time if all it's treasures were only useful in Assault? If PvP offered the best drops in the game, people would flock to it regardless of liking for the event, much like the Dynamis or the aforementioned Salvage. Popularity is a shaky argument simply because the popularity of the popular events already hinges on the rewards offered.
But, that's beside the point. Rewards offered from PvP don't have to be exclusive-top-of-the-line-get-this-or-ur-gimp treasure, it could be as simple as side-grades to currently offered stuff, or -1s of rewards from more popular events. There's even the option of borrowing from BCNMs and offering alternative NM drops.
All of the above can satisfy both the regular PvP enthusiast while maybe occasionally enticing someone who isn't normally interested. The point is to offer rewards that aren't super-niche space-takers.